Gel electrophoresis is a widely used technique for separating, analyzing, and purifying various biological molecules such as deoxyribonucleic acid (DNA), ribonucleic acid (RNA), polypeptides, proteins, and also nanoparticles, and other materials. As such, gel electrophoresis is extensively employed in many fields, for example biotechnology, molecular biology, biochemistry, medicine, pharmaceutical sciences, fisheries sciences, veterinary medicine, nanotechnology, and other fields.
In gel electrophoresis, an electric field is applied to move molecules through gel matrix, and the electrophoretic mobility of each molecule depends not only on its charge, size, and shape, but also on the physicochemical properties of a gel matrix such as pH value, salts composition, and the pore size of the gel matrix. Therefore, it is desirable for successful gel electrophoresis system to produce consistent gel matrices to separate molecules.
In conventional vertical gel electrophoresis, a cassette is assembled in upright position to house a buffered gel matrix between two flat plates, typically transparent glass plates or plastic plates. To prepare a gel, the two plates are separated by spacers arranged along the plate edges of two opposite sides. The bottom of cassette is sealed either by placing on the rubber gaskets of casting stands or by using other means, such as additional spacer, tape, agarose, or petroleum based material, followed by preparation and casting of buffered gel matrix. The gel matrix is made of a type of cross-linked polymer, usually polyacrylamide or agarose, and has wells for holding the samples to be analyzed. Care must be practiced during cassette assembly to prevent the gel matrix leakage. The whole procedures are labor intensive, time consuming, and error prone and involve using hazardous chemicals such as polyacrylamide and TEMED (Tetramethylethylenediamine). At the end of electrophoresis, the gel matrix is removed for subsequent analysis, and all components of the cassette must be thoroughly washed for reuse. Additionally, there is an incurring cost of replacing damaged or misplaced components of the cassette.
Alternatively, pre-cast gels enclosed in plastic cassettes produced by manufacturers can be purchased for gel electrophoresis. Regardless of whether pre-cast gels or self-made gels are used, an electrophoresis system apparatus with specific configuration must be used to accommodate the particular dimension of gel cassettes. Once the gel cassette is assembled into the electrophoresis system apparatus, a buffer solution is filled into two reservoirs in the apparatus to make contacts with the top and bottom of the gel matrix. After sample loading, the electrophoresis system apparatus delivers electrical current coming from a power supply through the gel matrix by using two electrodes in the buffers. Even though there are several electrophoresis system apparatus designs, all apparatuses essentially provide two reservoirs for a buffer solution(s) and have a platinum (or other metals or alloys of the platinum metal group) electrode in each reservoir. These electrophoresis system apparatuses are expensive, need a large amount of buffer to run, demand constant maintenance such as washing, and require a specific dimension of the gel cassettes, both pre-cast gels and self-made gels.
U.S. Pat. No. 8,361,293 B2 and U.S. Pat. No. 8,361,294 B2 describe a monolithic electrophoresis gel system, one-piece electrophoresis apparatuses that can be used directly without assembly or modification. However, the all-in-one unit requires an additional device in form of a lid that must be in specific dimension to fit on the top surface of the units. In addition to limiting user choice, the lid is suggested to have electrodes made of an electrically conductive material such as platinum, titanium, platinized titanium, and the like. The monolithic electrophoresis gel system uses an additional apparatus to provide an electrical current, just like current electrophoresis system apparatuses; it locks users into using a preset combination, puts extra cost, and loads additional handing step and maintenance. The monolithic electrophoresis gel system may have the advantage over current electrophoresis system apparatuses using pre-cast gels in that the monolithic electrophoresis gel system supplied with buffer.
These systems as disclosed in the prior art references usually require additional apparatus or components, and thus not fully independent. Generally, external electrodes need to be supplied at the point of the electrophoresis. Furthermore, these systems as disclosed do not provide a fully prefabricated gel electrophoresis module, which is self-contained and ready for electrophoresis.
Consequently, there is a need for a pre-cast gel electrophoresis system that is low cost, maintenance free, and ready-to-use without dependence on an additional form of apparatus. Such self-contained gel electrophoresis system can be manufactured in any dimensions, hence further expanding gel electrophoresis technique applications such as mobile capacity (use outside of typical laboratory settings) and high-throughput screening capability (large sample number screening).